Comparative analysis of Spectral and Deterministic methods for estimating fatigue life in joint of fixed jacket platform in the Andaman Sea Myanmar

Abstract

Cyclic wave loads can cause fatigue of the joints in the Jacket Platform structure, which is made of steel material and is prone to vibration resonance. This study compares the fatigue life of the Yetagun North Field (YET-D) jacket platform analyzed using the spectral and deterministic fatigue methods using the API RP-2A WSD standard and adding the Weld Improvement Technique 3D visual model and the analysis is processed using the Structure Analysis Computer System (SACS) Connect Edition v11.3 software. Fatigue analysis of Spectral Method without Weld Improvement Technique has exceeded the service life of 20 years, while some joints are less than the service life using the Deterministic Method, but after the Weld Improvement Technique using the S-N curve WJ3 the joint life increases to exceed its service life. The most critical joint 2043, has a fatigue life of 2.79 years for deterministic fatigue and 64.04 years for spectral fatigue. When WJ3 was applied, the fatigue life increased to 21.3 years and 514.8. Analysis of the fatigue life of Spectral and Deterministic Fatigue Method couplings based on the location of the elevation Joints with the same type of fatigue life will increase when approaching 0 m elevation from the seabed, but the Deterministic Method has a smaller life ratio than the Spectral.